Hamid Reza Salemi; Ali Reza Tavakoli
Abstract
Introduction: Water crisis as a majorlimitation factor for agriculture, like other arid and semiarid regions exists in Isfahan province which is located in the central part of the Zayandehrud River Basin (ZRB). Rice appears to be the far-most profitable crop but at the same time it has a major impact ...
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Introduction: Water crisis as a majorlimitation factor for agriculture, like other arid and semiarid regions exists in Isfahan province which is located in the central part of the Zayandehrud River Basin (ZRB). Rice appears to be the far-most profitable crop but at the same time it has a major impact on basin scale water resources, especially affecting downstream farmers. In the study area (ShahidFozveh Research Station), the water resources for agricultural production face heightened competition from other sectors like industry and domestic use. This necessitates considering different crops, altered agricultural systems and innovative methods that can reduce the water requirements for the irrigation of rice. The Alternative Wetting and Drying (AWD) seems to be an effective method reducing water use for rice crops and possibly save the water for downstream users. There have been no qualitative evaluations of rice production under deficit irrigation practices in Isfahan area. This study sought to determine, under study area conditions, the quantities of water irrigation used with AWD practices, the resulting water productivity (WP) and the effects of alternative irrigation management on yield, quality indices and rice production performance.
Materials and Methods: The ZRB (41,500 km2) is a closed basin with no outlet to the sea. The research was conducted in the Qahderijan region of Isfahan province, which is located in the central part of the ZRB. The ShahidFozveh Agricultural Research Station (32°, 36’ N, 51°, 36’ E) is located at the altitude of 1612 m above the sea level. In order to improve WP and illustration of the impact of various levels of flooding depth on grain yield and quality indices at rice production, a field experiment (3000 m2) was conducted at ShahidFozveh Research Station for 2 years arranged in a split plot design with three replications. It will be necessary to use different scenario of water flooding depth management to achieve the highest irrigation application efficiency and WP. The treatments included: three levels of irrigation managements I1: permanentflooding under 3.5 cm water during growth period, I2: permanent flooding under2.2cm water during growth period and I3: 0-1.5cm. (AWD) were considered as main plots and eight advanced rice cultivars (Geredehmahali, Zayandeh-rud, Sazandegi , Hasani, 67-97, 67-113, 67-47 and 67-72) as sub plots. The treatments were compared based on grain yield and quality indices for irrigation management and rice varieties including: amylose content (AC), Gelatinization temperature (GT) and gel consistency (GC). Production (grain yield), quality indices, the consumption water, WP and cultivars reactions to different irrigation management were evaluated in different treatments. The soil of the experimental area, according to USDA Soil Taxonomy 1994 is of FINE CLAYEY. At the soil depth of 1m, soil salinity (6.2 dS.m-1), water salinity (3.9 dS.m-1), and soil moisture at saturated capacity (48 Vol. %) at the field site were measured or experimentally obtained in the Isfahan Soil and Water Laboratory. The results were subjected to an ANOVA to analyze the effects of the treatments and their interactions using PROC GLM (SAS 9.1, SAS institute Ltd., USA). Duncan’s multiple range tests at 0.05 probability level was used for paired mean comparison.
Results and Discussion: Results showed that water flooding depth treatments had significant effect on gel consistency, geletination degree and WP (P0.01). Significant differences (P0.01) were noticed in Gelenation degree, gel consistency, grain yield, WP among the cultivars. Also cultivars have significant effect (P0.05) on amylose contents. The highest magnitude of WP was calculated 0.91kg.m-3for (I3) followed by Zayandehrud, 67-113 and Sazandegi with 0.86 and 0.85, respectively. Maximum WP obtained from AWD irrigation management and Zayandehrud rice variety, its amount was 9.1kg.mm-1. At this treatment with 33.4 percent reduction of irrigation water, have resulted only 11.1 percent decreased of paddy grain yield. Results showed that it is not necessary to maintain the rice field submerged in whole growth period. Considering the importance of water flooding depth optimization as the main scope in arid and semi-arid lands of Iran, (I3) is recommended.
Conclusion: During the two years of conduction of an experiment in ZRB with clay texture and mild saline water with the three (3) irrigation treatments imposed on the rice crop. The highest WP was achieved for (I3) followed by Zayandehrud, 67-113 and Sazandegi, respectively. It was found that the AWD irrigation management, despite its lower yield than other irrigation treatments, increased water productivity. Thus, this treatment is desirable therefore highly recommended for agricultural rice production in arid region.
Ghamar Fadavi; Javad Bazarafshan
Abstract
Introduction: As the statistical time series are in short period and the meteorological station are not distributed well in mountainous area determining of climatic criteria are complex. Therefore, in recent years interpolation methods for establishment of continuous climatic data have been considered. ...
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Introduction: As the statistical time series are in short period and the meteorological station are not distributed well in mountainous area determining of climatic criteria are complex. Therefore, in recent years interpolation methods for establishment of continuous climatic data have been considered. Continuous daily maximum temperature data are a key factor for climate-crop modeling which is fundamental for water resources management, drought, and optimal use from climatic potentials of different regions. The main objective of this study is to evaluate different interpolation methods for estimation of regional maximum temperature in the Isfahan province.
Materials and Methods: Isfahan province has about 937,105 square kilometers, between 30 degree and 43 minutes to 34 degree and 27 minutes North latitude equator line and 49 degree and 36 minutes to 55 degree and 31 minutes east longitude Greenwich. It is located in the center of Iran and it's western part extend to eastern footage of the Zagros mountain range. It should be mentioned that elevation range of meteorological stations are between 845 to 2490 in the study area. This study was done using daily maximum temperature data of 1992 and 2007 years of synoptic and climatology stations of I.R. of Iran meteorological organization (IRIMO). In order to interpolate temperature data, two years including 1992 and 2007 with different number of meteorological stations have been selected the temperature data of thirty meteorological stations (17 synoptic and 13 climatologically stations) for 1992 year and fifty four meteorological stations (31 synoptic and 23 climatologically stations) for 2007 year were used from Isfahan province and neighboring provinces. In order to regionalize the point data of daily maximum temperature, the interpolation methods, including inverse distance weighted (IDW), Kriging, Co-Kriging, Kriging-Regression, multiple regression and Spline were used. Therefore, for this allocated data (24 days for each year and 2 days for each month) were used for different interpolation methods. Using difference measures viz. Root Mean Square Error (RMSE), Mean Bias Error (MBE), Mean Absolute Error (MAE) and Correlation Coefficient (r), the performance and accuracy of each model were tested to select the best method.
Results and Discussion: The assessment of normalizing condition of data was done using Kolmogrov-Smirnov test at ninety five percent (95%) level of significance in Mini Tab software. The results show that distribution of daily maximum temperature data had no significant difference with normal distribution for both years. Weighed inverse distance method used for estimation daily maximum temperature, for this purpose, root mean square error (RMSE) for different status of power (1 to 5) and number of station (5,10,15 and20) was calculated. According to the minimum RMSE, power for 2 and number of station for 15 in 2007 and power for 1 and number of station for 5 in 1992 were obtained as optimum power and number of station. The results also show that in regression equation the correlation coefficient were more than 0.8 for the most of the days. The regression coefficient of elevation (h) and latitude (y) were almost negative for all the month and the regression coefficient of longitude (x) was positive, showing that decreasing temperature with increasing elevation and increasing temperature with increasing longitude. The results revealed that for Kriging method the Gussian model had the best semivariogram and after that spherical and exponential were in the next order, respectively for 2007 year. In the year 1992, spherical and Gussian models had better semivariogram among others. Elevation was the best variable to improve Co-kriging method as auxiliary data. such that The correlation coefficient between temperature and elevation was more than 0.5 for all days. The results also show that for Co-Kriging method the spherical model had the best semivariogram and after that the exponential and Gussian were in the next order, respectively for 2007 year. In the year 1992, the best model of semivariogram was the linear model and after that the spherical and Gussian models had better semivariogram in the next order.
Conclusion: The results revealed that the application of multiple regression method for interpolation produced less errors between observed and estimated maximum temperature in 1992 (RMSE ranges from 1.41 to 4.03, MAE ranges from 0.98 to 2.55, and r ranges from 0.61 to 0.95). For 2007 year, the best estimation was performed by multiple regression and Kriging-Regression (RMSE=ranges from 0.99 to 3.98, MAE ranges from0.77 to 2.92, and r ranges from 0.32 to 0.97). Kriging, Co-Kriging, IDW, Spline methods were also reasonably performed well and could be used as the second order of priority .In addition, with increasing number of stations in 2007 as compared to 1992, the overall accuracy of model performance in estimation of daily maximum temperature have been improved.
